FIG. 1 shows an example of the conventional developer feeder for wet developing apparatus. A photoconductor drum a as a latent image retainer has one developing roller b engaged therewith rotatably at a peripheral speed identical to that at which the drum is rotated, and the developing roller b is supplied with a liquid developer from a feed roller c (see, for example, JP H11-202631 A).
While the feed roller c in this conventional developer feeder has its peripheral surface smooth, a developer feeder is also known using as the feed roller an anilox roller which is formed on its peripheral surface with minute projections and recesses and rotated in a direction opposite to that in which the developing roller b is rotated (see, for example, JP 2001-202662 A).
The developing and feed rollers b and c are such that imparting an adequate close distance and/or contact pressure between their surfaces while applying an appropriate voltage difference (e. g., 200 V) between them allows toner particles of the liquid developer to electrophoretically migrate toward and deposit on the lower potential surface to form a thin uniform developer film on the developing roller b.
In the developer feeder of this type, however, an assembling error of the developing and feed rollers and their dimensional errors at the time of manufacture inevitably cause their axes to be skewed and their cross sections to become out of round and to be decentered with the result that the contact pressure and close distance become uneven for roller axial directions or angles of rotation and in turn that the thin developer film layer supplied onto the developing roller becomes out of constant in thickness and in turn that the development density onto the photoconductor drum becomes uneven and hence the images transferred may become poor in density.
While to overcome this inconvenience there is a developer feeder using as a feed roller an anilox roller (mesh roller) having formed on its surface with minute projections and recesses as shown in JP 2002-202662 A, the problem arises there that the minute projections and recesses on the feed roller come to remain transcribed in the thin developer film layer on the developing roller as well as the problem that the feed rate of liquid developer cannot be changed unless the rollers are each changed with another and the problem of premature wear of the developing and feed rollers due to their rotating in opposite circumferential directions.